Zhiming Tao

Faraday anomalous dispersion optical filter with a single transmission peak using a buffer-gas-filled rubidium cell

A Faraday anomalous dispersion optical filter (FADOF) with a single transmission peak is achieved by using a buffer-gas (argon, 2 Torr)-filled rubidium cell. At room temperature, the transmission is 0.2% and the bandwidth of the transmission peak is 0.65 GHz. At a temperature of 63° C, the transmission rises to a maximum of 30.6%, with a bandwidth of 1.41 GHz. This FADOF may replace the use of interference filters or virtually imaged phased arrays in imaging modalities.

Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications.

Faraday laser using 1.2 km fiber as an extended cavity

We demonstrate a Faraday laser using a 1.2 km fiber as an extended cavity, which provides optical feedback and obtains small free spectrum range (FSR) of 83 kHz, and have succeeded in limiting the laser frequency to a crossover transition of the natural 87Rb at 780 nm. The Faraday laser is based on a Faraday anomalous dispersion optical filter (FADOF) with an ultra-narrow bandwidth and the long fiber extended cavity of 1.2 km. The peak transmission assigned to the crossover transition in the FADOF is 20.5% with an ultra-narrow bandwidth of 29.1 MHz. The Allan deviation of the Faraday laser is around in 0.06 to 1 s sampling time. Laser frequency is always kept in the center of the transmitted peak assigned to . The Faraday laser realized here can provide light exactly resonant with an atomic transition used for atom–photon interaction experiments and is insensitive to diode temperature and injection current fluctuations.

Distribution of populations in excited states of electrodeless discharge lamp of Rb atoms

The intensity of fluorescence spectral lines of Rb atoms in the region of 350–1110 nm is measured in eletrodeless discharge lamp. The population ratio between the excited states is calculated according to the spontaneous transition probabilities with rate equations. At the same time, the population density of energy level is also obtained. The results provide the potential applications of electrodeless discharge lamp in atomic filter and optical frequency reference at higher excited states without a pumping laser.

Electrodeless-discharge-vapor-lamp-based optical atomic filter

An excited-state Faraday anomalous dispersion optical filter (FADOF) has been demonstrated, which utilizes a rubidium electrodeless-discharge-vapor-lamp rather than an external pump laser. When the lamp is turned off, the lamp-based filter can be treated as a ground-state FADOF. The compact lamp based FADOF holds promise for realing a frequency-fixed diode laser systems (such as a 1529 nm laser for optical communication application) and a multi-frequency filters.

Research on Cs active Faraday optical frequency standard with 459 nm laser pumping

Known as a unique optical clock, active optical clock has prior advantages to surpass the limitation of the conventional optical clock in potential stability. In this paper, we proposed an improved Cesium active Faraday optical frequency standard with 459 nm laser pumping. This scheme reduces the residual Doppler broadening in previous results with 852 nm laser pumping. The transmission is 2.4% and the bandwidth of the transmission peak is 12.3 MHz. It greatly narrows the bandwidth of Faraday anomalous dispersion optical filter and decreases the length of the bad cavity used in Cesium active Faraday optical frequency standard. This will be very helpful for further suppression of cavity pulling effect.

Diode laser using narrow bandwidth interference filter at 852 nm and its application in Faraday anomalous dispersion optical filter

We demonstrate an 852-nm external cavity diode laser (ECDL) system whose wavelength is mainly determined by an interference filter instead of other wavelength selective elements. The Lorentzian linewidth measured by the heterodyne beating between two identical lasers is 28.3 kHz. Moreover, we test the application of the ECDL in the Faraday atomic filter. Besides saturated absorption spectrum, the transmission spectrum of the Faraday atomic filter at 852 nm is measured by using the ECDL. This interference filter ECDL method can also be extended to other wavelengths and widen the application range of diode laser.